The so-called sliding roof type vehicles are well known which are provided with an opening section in a roof and said opening section is covered so as to be opened or closed. As shown in FIG. 16, a vehicle of a type whose opening section in its roof can be opened or closed with a cover member (hereinafter referred to as a sliding roof type vehicle) 501 is provided with a wide opening section 502a in its roof 502. Along its slide rails (not shown), which are provided along both sides of the opening section 502a, multiple sliding members for supporting both edges of the cover member 503 are mounted slidably in a front-and-rear direction. The multiple sliding members are provided on both sides of the cover member 503 in a longitudinal direction and at specified intervals.
With the structure, the opening section 502a of the roof 502 can be closed by moving each sliding member along the slide rails toward the front of the vehicle, thus spreading the cover member. On the contrary, by moving each sliding member toward the rear end of the vehicle along the slide rail, the opening section 502a of the cover member 503 is folded around the rear end of the vehicle to open the section 502a. 
With the sliding roof structure, the folded cover member 503 occupies some part of the rear area of the opening section 502a by the length L1 in the longitudinal direction, and swells upward from the roof 502. Consequently, the opening section 502a of the roof 502 is limited to L2, which is shorter by L1 than the total longitudinal length L of the opening section, thus making the opening section 502a of the roof 502 smaller and damaging the appearance of the vehicle.
When the rear window 504 is opened, the rear end 502b of the roof 502 and the folded cover member 503 exist between the opening section of the rear window 504 and the opening section 502a of the roof 502, which spoils the sense of openness when the rear window 504 is opened.
JP2005-313737A discloses a roof storage structure of a vehicle provided with a storage space for constructional elements of the roof at the back of the rear seat of the vehicle. This structure stores the constructional elements of the roof in a packaged tray, which is rotated by a rotating mechanism, and stored in the storage space.
JP2002-046473A discloses a convertible automobile that the roof is supported in a state in which the front and the rear sides of the roof are movable along the vehicle body. The front and the rear sides of the roof are stored in a roof storage chamber. The front side of the roof is oscillated when it comes down into the roof storage chamber by the function of the oscillation support device, and stored there diagonally or virtually vertically.
JP2003-507244 (WO01/014157) discloses a cassette constituting a rear window that can be slid along the arch-like side panel of a vehicle, a flexible roof module, which can be removed in overlaid state, and a vehicle equipped with the cassette and the module.
In the roof storage structure described in the above-mentioned JP2005-31373A, the storage space for members comprising the roof is relatively large, and especially long in the longitudinal direction, minimizing the passenger space and thus sacrificing the convenience.
In the roof of an convertible vehicle described in the above-mentioned JP2002-046473A, the storage space for the roof is as large as in the case of a roof storage structure described in JP2005-313737A, which also makes the passenger capacity small and sacrifices convenience.
With the removable roof module in JP2003-507244A (WO01/014157), the cassette and flexible roof devices slide along the side panel on the roof, and stored in the storage unit under the floor of the trunk. Since its covering module has a complicated structure, in order to store the cassette and the flexible roof devices, the rear hatch must be opened first, the floor of the trunk must be pulled toward the rear side, and then the cassette and the flexible roof devices must be taken into the storage unit. The storage thus requires complicated operations, making it difficult to store or extend the roof while the operator is sitting in the vehicle.
It is an object of the present invention to provide a cover member storage structure of a sliding roof vehicle that allows the covering member comprising the roof to be stored in folded state without sacrificing the trunk space, and ensures large opening area in the roof while the cover member is stored.